Baker told Robert Caro that he could've but didn't, ditto a lot of other VIPs.
Actually, Caro makes clear that Baker is one of the interviewees he's
never got [p.617, hardcover edition].
What Caro does argue in the newly released volume of LBJ's biography is that the LIFE magazine investigation into LBJ's non-Baker related (or ostensibly non-Baker related) fortune was the real landmine for Johnson. That was the political smoking gun, as it couldn't be subsumed into byzantine white collar crime investigations, as Baker was.
Yet I did get the impression from that narrative that the Baker scandal, if it had somehow exploded, probably also snares JFK, because of the callgirl ring Bobby ran--Caro doesn't say as much, but I definitely grokked "Oh, by the way, Jack could be easily identified as having used the services of those women, not Johnson, but this isn't a bio of Kennedy so I'm not going to say so explicitly."
Also, AFAIK the thing with the Baker scandal is that the senate rules committee did investigate it, with the ranking GOP senator (John Williams of Delaware) being very, very keen on exposing the truth--yet there was a deep institutional desire to minimalise the fallout of it all. I assume this was because Republicans as well as senate Dems could have been burnt.